Pour the broth into large pot and bring to a boil. Add the garlic, onion, parsnip and chicken, reduce the heat and simmer, covered, for 1 hour. Remove the chicken and place in a large bowl to cool, then shred it with your fingers. Discard the bones and set aside. Add the carrots, celery, zucchini, squash and parsley to the pot and continue to simmer for 30 minutes, leaving the lid slightly open, until vegetables soften. Season with salt to taste. Divide the shredded chicken among six bowls, ladle the soup on top, and serve.